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O: Fachverband Oberflächenphysik

O 102: Heterogeneous Catalysis on Metals

O 102.9: Vortrag

Donnerstag, 19. März 2020, 12:45–13:00, TRE Phy

Atomistic simulation of the surface reactions: O2, H2O and CO adsorption and dissociation on Zr- and B-terminated ZrB2(0001) surfaces — •Yanhui Zhang and Stefano Sanvito — CRANN, Trinity College Dublin, Dublin, Ireland

ZrB2 as a prototypical ultra-high temperature ceramic (UHTC) in combustion environment of aerospace applications are exposed to chemically aggressive gases like O, CO and H2O etc.. A detailed picture of the different channels of surface reactions involved are important for the development of ablation-resistant hot sections of the next generation aircraft. In this work, we have systematically studied the adsorption and dissociation of O2, CO and H2O on multiple active sites of ZrB2 (0001) surfaces by atomistic simulations based on density functional theory. The adsorption strength of O2 is the highest, followed by CO, and lastly H2O. Meanwhile, the hollow and bridge sites are largely preferred. The dissociative adsorption of O2 without activation barriers prevail in case of lateral approaching. Interestingly, the surface reconstruction of B-terminated (0001) surface is also observed to mediate surface reaction processes. Additionally, the surface reaction phase diagrams have been built up by searching the reaction barriers by climbing-image NEB method. Our results indicate the activation energy barriers of CO are the highest, while those of O2 are the lowest. This work provides insights into the initial processes of surface reactions at atomistic scale, and highlights the importance of surface treatment to the final performance of UHTC materials.